Wrenches are fastening tools that are used to tighten and loosen various types of fittings such as bolts and nuts. Wrenches typically employ a square shaped male drive that is attached to complimentary female shaped drives of removable sockets. Sockets of appropriate sizes and configurations are placed onto the desired fitting and the wrench can be rotated, for example by hand, so that the socket in turn applies torque to the fitting to effect its loosening or tightening. The wrench is provided with a ratcheting mechanism that allows the wrench to be turned without having to lift the device off of the fitting that is being tightened or loosened. Wrenches are usually reversible by way of an internal mechanism that can be actuated in order to switch between tightening and loosening while the wrench is turned in the same direction.
Impact wrenches are known for use in high torque applications such as product assembly, vehicle servicing, heavy equipment repair, and building construction. Impact wrenches may be pneumatically, hydraulically or electrically driven and can be generally linear in shape or may resemble a pistol in other variations. Impact wrenches typically have a square male drive to which a socket may be attached that can be subsequently fit onto the fitting that is to be secured or loosened. The socket may be attached to the square male drive by way of a spring-loaded pin in the square male drive that is received within a complimentary recess of the socket. Alternatively, a hog ring arrangement can be used to hold the socket onto the square male drive, or a pin can be employed to secure the socket to the square male drive. The user can actuate the impact wrench by pressing a button which causes a high torque impact to be imparted onto the socket and fitting.
Adapters are often used to allow wrenches that have a square male drive of a certain size to be used with sockets that have a differently sized female drive. Adapters include a female drive fitting that accepts the male drive of the wrench and a male drive fitting that accepts the female drive of the socket. Adapters for use with hand wrenches are made of a strong steel while adapters for use with impact wrenches are typically made of a more malleable steel. Weaker steel is used in impact adapters since high tightening forces are present. In this regard it is desired to have an adapter that is overstressed flex and then tear apart instead of being shattered and potentially causing injury to the user. Since impact adapters are made of weaker materials they may fail during use thus wasting time and increasing cost of use of the impact wrench.
FIGS. 1 and 2 illustrate a wrench adapter 100 that has a curved flange 102 that terminates at four planar ledges 104 located adjacent the sides of a male drive 108 of the wrench adapter 100. The planar ledges 104 are oriented so that they each have a planar normal that extends parallel to the longitudinal axis 106 of the wrench adapter 100. Insertion of the male drive 108 into a complimentary female drive of a socket and subsequent turning of the wrench adapter 100 by an impact wrench or the like results in the application of force to the curved flange 102 and the planar ledges 104. The arrangement of the male drive 108 and the planar ledges 104 causes a stress concentration to be realized that results in fracture of the wrench adapter 100 and ultimate failure. As such, there remains room for variation and improvement in the art.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention.